<description><para>The dns module leverages libudns to allow highly concurrent DNS lookups of a variety of DNS RR types. In the event that you name a dns check <parameter>in-addr.arpa</parameter> with an rtype of <parameter>PTR</parameter>, the result of the query may be used throughout reconnoiter as the identifying hostname of that target.</para>

<para>This module provides the <function>inaddrarpa</function> interpolation method which will reverse a dot-delimited IP address. This is particularly useful for constructing in-addr.arpa queries, but also used for checking blacklists, whitelists and other IP-based DNS databases.</para>

allowed=".+">The domain name server to query. If the name of the check is in-addr.arpa, the system default nameserver is used. Otherwise, the nameserver is the %[target_ip] of the the check. If set to the string "default" the underlying system default nameserver is used.</parameter>

allowed=".+">The query to send. If the name of the check is in-addr.arpa, the reverse IP octet notation of in-addr.arpa syntax is synthesized by default. Otherwise the default query is the name of the check itself.</parameter>